Oxygen acquisition is easier in air than in water because:
a. oxygen content of air is higher than that of water.
b. oxygen diffuses more slowly in water than in air.
c. more energy is required to move water than air because water is denser.
d. solubility of oxygen in water is relatively low.
e. all of the above.

Many organizations release indexes used to measure the development of the world's countries. as we learned in this lesson, these indexes measure many factors, from life expectancy to happiness. in your opinion, what are the three most important factors we can use to determine how developed a country might be? explain your answers in a few sentences.